A re-evaluation of the mitogenic effect of serotonin on vascular endothelial cells.

Serotonin is an extracellular mediator recognized by seven different types of receptors, thus giving rise to pleiotropic intracellular responses. One of these responses is the activation of proliferation for a number of cell types. The induction of proliferation of otherwise quiescent endothelial cells is a key step of angiogenesis. Previously published work concerning the effect of serotonin on endothelial cell proliferation is controversial. The present work is aimed to re-evaluate the mitogenic role of serotonin on endothelial cells, since a pro-angiogenic role for serotonin could be hypothesized if its mitogenic potential on these cells were confirmed. By using three different types of endothelial cells and three experimental approaches, we demonstrate that serotonin cannot be considered a general mitogen for endothelial cells.